In general, earthmoving machines such as wheel loaders, excavators, track-type loaders, and the like are used for moving mass quantities of material. These earthmoving machines have work implements that can include a bucket. The bucket is controllably actuated by at least one hydraulic cylinder. An operator typically performs a sequence of distinct operations to capture, lift and dump material (i.e., to dig material) with the bucket by way of the hydraulic cylinder(s).
A typical sequence can include the operator first positioning the bucket near the ground surface and close to a pile of material. The operator then directs the machine forward to engage the pile of material. Next, the operator lifts the bucket to generate a downward force on the machine that maintains traction, and then racks (tilts) the bucket back to capture the material. The operator then moves the earthmoving machine to a desired dump location, and dumps the captured material from the bucket. Next, the operator moves the earthmoving machine back to the pile of material and repeats the sequence.
The performance of the typical sequence may be inefficient under certain circumstances because the machine may waste energy and time needlessly pushing the material into the pile rather than pushing the material upward out of the pile. Specifically, the material may be needlessly pushed into the pile when the operator directs the machine forward and when the operator lifts the bucket. Wasting energy may increase fuel consumption of the machine, thereby increasing the operating costs of the machine. Moreover, wasting time may reduce the number of sequence repetitions completed during a given time period. Thus, the machine may fail to maximize an amount of material moved during the given time period.
One way to increase the efficiency of an earthmoving machine may be to alter the typical sequence. An example of this strategy is described in U.S. Pat. No. 6,385,519 (the '519 patent) issued to Rocke on May 7, 2002. The '519 patent describes driving a machine, such as a loader, with a bottom of a bucket nearly level and close to the ground, toward a pile of material. After a tip of the bucket contacts and begins digging into the pile of material, an electronic controller generates command signals to simultaneously lift and rack the bucket through the pile of material while the loader continues to be driven forward. This lifting and racking of the bucket maximizes a traction of the loader and allows the bucket to cut upward while letting material slide to a back portion of the bucket. The sequence relieves drivetrain torque by racking the bucket, thereby reducing a resistance of the pile of material. Reducing the resistance of the pile of material reduces drivetrain stalls and wheel slippage.
Although the strategy of the '519 patent may help reduce the resistance of the pile of material by simultaneously lifting and racking the bucket, the strategy may be difficult to implement without the electronic controller of the '519 patent. Specifically, it may be difficult for an operator to simultaneously lift and rack the bucket while driving toward the pile. It may be especially difficult for the operator to simultaneously lift and rack the bucket while driving toward the pile if the bucket is attached to the loader by a torque parallel linkage. Moreover, though the sequence of the '519 patent may help reduce the resistance of the pile as the bucket is first lifted, the sequence of the '519 patent may do little to reduce the resistance of the pile before the bucket is first lifted. This is because the bottom of the bucket of the '519 patent may not be racked until the bucket is first lifted. Thus, energy may be wasted needlessly pushing the material into the pile before and/or while the bucket is first lifted.
The disclosed system and method are directed to overcoming one or more of the problems set forth above and/or other problems in the art.